1. Field of the Invention
The present invention relates to a communication apparatus capable of making wireless communication without using an access point, a communication system, and a computer program that is executed by a computer controlling the above-mentioned communication apparatus.
2. Description of the Related Art
Conventionally known are systems such as ad hoc and wireless fidelity (Wifi) direct with which a plurality of apparatuses make communication without using an access point, by using a transmission standard such as the IEEE802.11n that is the same as that of a wireless local area network (LAN).
To make communication with the communication systems, it is necessary to perform setting of a wireless network rightly on the communication apparatuses that make communication. The setting includes various items such as an internet protocol (IP) address, a subnet mask, an authentic system, an encryption system, and an encryption key corresponding to the encryption system. It is difficult for a user with little knowledge to perform setting of the wireless network from scratch.
For coping with this point, Japanese Laid-open Patent Publication No. 2011-188238 discloses a terminal that generates a service set identifier (SSID) by using an IP address and a terminal identifier thereof and generates a beacon signal containing the SSID. The communication apparatus enables another terminal that has received the beacon signal to acquire the IP address of the terminal that is a transmission source, from the SSID contained in the beacon signal and make connection by using the acquired IP address.
It should be noted that the SSID is used as an identifier for identifying an access point in the wireless LAN communication standard of the IEEE802.11 series. Each access point and each terminal apparatus communicate with only terminal apparatuses having an identical SSID generated. Accordingly, the SSID can be a network identifier for identifying a network that each apparatus joins.
Furthermore, in the communication without using an access point, the communication apparatus that outputs the beacon signal and receives connection from another apparatus serves a function corresponding to the access point.
A state where a plurality of communication apparatuses having a common SSID and IP address are present can be made due to setting mistake or the like in some cases. When the apparatuses are present at close positions and the communication apparatus that receives connection transmits the beacon signal, the following failure occurs. That is, another communication apparatus that requests connection cannot make communication normally even if another communication apparatus tries to make communication with the communication apparatus to which it desires to be connected based on the received beacon signal. This is because the SSID and the IP address overlap and the communication apparatus cannot identify a communication party normally. When a plurality of frequency channels can be used, the above-mentioned failure occurs when the frequency channel that is used is also common.
To avoid this state, it is sufficient that a user operates the communication apparatus transmitting the beacon signal to change setting of the SSID (or information that is used for generating the SSID), the IP address, or the frequency channel so as to eliminate overlap of the SSID, the IP address, or the frequency channel.
This, however, arises a problem in that the change of the setting of this type imposes a heavy burden on the user with little knowledge relating to network communication.
The technique described in Japanese Laid-open Patent Publication No. 2011-188238 as mentioned above cannot solve the problem that occurs due to the overlap of the setting. In addition, the problem can occur in the same manner even when wireless communication standards other than the IEEE802.11 series are used.
In view of the above-mentioned background, there is a need to enable a user with little knowledge relating to network communication to avoid failure of wireless communication due to overlap of setting easily.